Fluid-pressure brake.



F. L'. CLARK.

FLUID PRESSURE BRAKE.

APPLICATION FILED NOV.2,190&

1 ,1O4=,775, Patented July 28, 1914.

INVENTOR rnANcIs n. CLARK, onrrrrssunerr, PENNSYLVANIA, Ass eNoR .ro THEWESTINGL HOUSE AIR BRAKE COMPANY, OF PIT'TS or PENNSYLVANIA.

Specification of Letters Patent. 7

BUneH,'1?ENNsYLv IA, A conronA'rroN FLUID-PRESSURE BRAKE.

PatentedJuly as, 1914..

Application filed November 2, 1906. Serial No. 341,668.

To all whom it may concern:

Be it known that I, FRANoIs L. CL RK, a citizen of the United States,residmg at Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented new and useful Improvements inFluid-Pressure Brakes, of which the following isi'a specification. a

'This invention relates to fluid pressure brakes, and more particularlyto that type of apparatus in which two brake cylinders are employed, oneof smaller diameter into which the fluid under pressure is firstadmitted for the purpose of taking up the slack in the brake-rigging andbringing the brake shoe against the wheels, and a secondand larger brakecylinder to which the fluid under pressure is then supplied for exertingthe final application of maximum power to the rigging and brake shoes.By means of this construction the advantages of the maximum brakingpower of the large brake cylinder are obtainedwith the expenditure of aminimum quantity of compressed fluid since the first cylinder, inwhichthe piston travel-isadequate for taking up the slack and applyingthe brake shoe to the wheels, is of small capacity, and the travel ofthe piston in thelarge cylinder is very; short, such as results onlyfrom the additional stretching of the brake rigging, due to the Y Y a jcylindersare located at right angles to each other',although they may bearr'angedin any other suitable or preferred relation.

tons of the respective cylindersto the brake contains piston 6 andspring? and has an greater power thus applied. a With this type ofapparatus, it is necessary to provide some" form of mechanism forconnecting the pisrigging in such a manner that the large piston mayexert its pressure upon the rigging at the point to which it hasbeenactuated or appliedby the first piston. Various forms of clutch deviceshave been'proposed for connecting the large piston to the brake rigging;and a toggle lever connectionhas also been employed actuated by thesmall piston; but the clutches have been found to gle lever, itsometimes happens that there is not enough slack to allow a sufficienttravel of the small piston to straighten the toggle 7 joint, in whichcase the small piston is liable to be forced back in its cylinder by thereaction from the power applied to the large piston, which must thenmake a com-' plete traverse to take up all the slack in the brakerigging and apply the brake shoes to the wheels.

' The principal object of my present invention is to provide an improvedform of mechanism-for connecting the brake pistons to the rigging,whereby the smaller primary piston may make any length of travel, eitherlong orshort, suflicient to bring'the brake blocks against the wheels,and the large or secondary piston then acts positively upon the riggingregardless of the length of travel of the primary piston and withoutforcing the sameback in its cylinder.

According to its preferred form, my invention comprises a wedgemechanism, or equivalent device, through which power on the small pistonactson the brakeriggingto take up the slack and so designed that whenthe small piston has made its traverse and the power is applied to thelarge piston, it

will then exert its force upon the brake rigglng in the position towhich it has been drawu up by the small piston, and without danger offorcing the small piston back in .its cylinder.

In the accompanying drawing; Figure 1 is a'sectional view of two brakecyllnders and connecting mechanism, illustrating one form ofconstruction embodying my improvements ;F1g. 2 an end vlew'of the brakecylinders; and Fig. 3 asection of the wedge mechanism take-n on theliner -w of Fig, 1. As shown in the drawing, the two brake The small, orprimary brake'cylinder, 5,

inlet pipe or port 8,through which air or 1 other fluid under pressuremay be supplied from a brake valve, triple valve or other device forcontrolling the application of the brakes. inder, "9, contains releasespring 11, and pis ton 10, preferably connected to the cylinder lever 12of the brake rigging.

be objectionable, and in the use of the togi The second andlarger brakecyl- Any desired form; of wedge device or equivalent mechanism may beemployed and actuated I by the primary brake piston for a curved lever15, which is preferably bifurcated and pivoted at one end to the end ofthe small cylinder 5, and connected at the other end by rod 16 to theintermediate pivot or fulcrum of the cylinder lever 12. A hearing block17 may be pivotally mounted on the wedge block for engaging the curved:

bearing surface 18 of the lever 15, which curved surface is socalculated that the nor- 1 mal outward travel of the small brake pistonand the wedge blockoperates through rod 16 to move the lever 12 of thebrake rigging sufiiciently to take up the slack and force the brakeshoes againstv the wheels with a certain pressure. During this movementthe cylinder lever turns about its lower connection to the large pistonas a fulcrum, then when the compressed air is admitted to the largecylinder and its piston is forced out the pressure is exerted upon thelower end of the lever 12, which then turns about its pivoted connectionto rod 16 as a fulcrum and thereby applies its force to the brakerigging in the position to which it has been previously stretched by themovement of the primary piston.

The curved lever 15, with its bearing surface, is so designed that thepower exerted thereon by the small piston is always greater than thecomponent of the force from the large piston, which reacts through saidwedge mechanism in the reverse direction when air is supplied to thelarge cylinder and the brake lever is turned about its connection withrod 16 as a fulcrum. By means of this construction the small piston willnot be forced back in its cylinder by the application of power to thelarge piston, but the fulcrum of the brakelever will be held at whateverposition it is advanced by the application of the brake shoes by thesmall piston and the greater power from the large piston will then beapplied at that position of the brake rigging. This will be the samewhatever maybe the length of travel made by the small piston,consequently it is not necessary that the small piston should make apredetermined length of stroke in order that the power of the largepistonmay be properly applied to the brake rigging in its advancedposition.

Any suitable or preferred means may be employed for admitting air underpressure to the large cylinder after the small primary piston has madeits stroke and brought the brake shoes against the wheels, such as aport controlled by said small piston or a valve device 20, as indicatedin Fig. 1, com.- prising a piston 21, spring 22 and slide valve 23,which operates when the pressure, in the small brake cylinder rises to apredetermined degree, to open asupply port 24 leading into the largebrake cylinder. This slide valve may also control an exhaust port fromthe large brake cylinder to the atmosphere,

my improvement the advantages of the greater braking power, due to thelarge piston, are obtained by the use of a minimum quantity ofcompressed air.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is

1. In a fluid pressure brake, the combination with a primary brakecylinder and piston and a second opposing brake cylinder and piston, ofa driving connection between the primary piston and the brake riggingand a movable resistance wedge for opposing the backward movement of thedriving connection to thereby prevent lost, motion of the second pistonwhen its pressure is exerted upon the brake rigging.

2. In a fluid pressure brake, the combination with a brake cylinder andpiston for exerting a preliminary pressure on the brake rigging and asecond brake cylinder and PIS? ton opposing the first brake cylinder andpiston for exerting the final pressure, of an operating connectlonbetween the first plston Y and the brake rigging and a movable wedge foropposing the backward movement of the operating connection in anyposltlon ofthe first piston to thereby prevent lost motion of 1 thesecond piston upon the application of pressure to said second piston.

3. In a fluid pressure brake, the combination with a brake cylinder andpiston for exerting a preliminary pressure on the brake rigging and asecond brake cylinder and piston opposing the first brake cylinder andpiston for exerting the final pressure, of a driving connection betweenthe first piston l and the brake rigging and a movable wedge foropposing the backward movement of the driving connection.

4. In a fluid pressure brake, the combination with a small or primarybrake cylinder and piston for taking up the slack and bring-v ing theshoes against the wheels, and a larger brake cylinder and piston forapplying the final pressure to the brake rigging, of a wedge mechanismwhereby the large piston may act positively on the rigging at what-vever position it is applied by the small piston. i

5. In a fluid pressure brake, the combination with a small brakecylinder and piston, and a larger brake cylinder and piston, of a wedgemechanism operating at the time of movement of the small piston forpreventing lost motion of the large piston when its pressure is exertedupon the brake rigging.

'6. In a fluid pressure brake, the combination with a small brakecylinder and piston to which the fluid is first admitted, and a largerbrake cylinder and piston to which fluid is subsequently admitted, of aWedge mechanism operated by the movement of the small piston for settingup the brake rigging to an applied position.

7. In a fluid pressure brake, the combination With a small brakecylinder and piston, and a larger brake cylinder and piston, of a Wedgemechanism through Which the small piston acts on the brake rigging totake up the slack and apply the brake shoes to the Wheels Without movingthe large piston.

8. In a fluid pressure brake, the combina tion With a small brakecylinder and piston, and a larger brake cylinder and piston, of a brakelever operated directly by the large piston, and a- Wedge mechanismoperated by the small piston and connected to another point of saidbrake lever.

9. In a fluid pressure brake, the combination With a small brakecylinder and piston,

and a larger brake cylinder and piston, of a Wedge mechanism actuated bythe small piston and comprising a wedge block and a Copies of thispatent may be obtained for lever having a bearing surface for engagingtherewith.

10. In a fluid pressure brake, the combination With a small brakecylinder and piston, and a larger brake cylinder and piston,- ofa Wedgemechanism actuated by the small piston and comprising a Wedge block anda a curved lever having a bearing surface for engagmg the wedge.

In testimony whereof I have hereunto set my hand.

FRANCIS L. CLARK. Witnesses:

R. F. EMERY, J. S. CUSTER.

five cents each, by addressing the Commissioner of Patents.

Washington, I). 0.

